Knife sharpening mechanism for cutting machines



Nov. 3, 1942. F. J. CLARK 2,300,535 KNIFE- SHARPENING MECHANISM FOR CUTTING MACHINES Filed May 1, 1941 2 Sheets-Skeet 1 [1,32 v V E 2/ -10 J g 5 25 [Z 5 :x 4Z Z I :5 mvzmons. & n v

.55 45 7f M /r 4.9 ATTORNEYS Nov. 3, 1942. F. J. CLARK I KNIFE SHARPENING MECHANISM FOR CUTTING MACHINES Filed May 1, 1941 2 sheets-shegtz Patented Nov. 3, 1942 i KNIFE SHARPENING MECHANISM FOR CUTTING MACHINES Frederick J. Clark and Carl F. Hilgeman, Buffalo,

N. Y., assignors to Eastman Buffalo, N. Y.

Machine Company,

Application May 1, 1941, Serial No. 391,365

11 Claims.

This invention relates to knife sharpening mechanisms for cutting machines, and more particularly to improvements in sharpening mechanisms for portable cutting machines of that type commonly used for cutting cloth and other sheet materials, which are moved relatively to the work in cutting the same, and have an upright, Vertically reciprocating knife.

Application for United States Letters Patent, Serial No. 314,666, filed January 19, 1940, by Frederick J. and Frederick G. Clark, discloses a machine of this type equipped with sharpening mechanism for the knife, comprising abrasive grinding means or elements which are power driven for performing their grinding action and are adapted to be moved up and down along the knife so as to sharpen the edge throughout its whole length. While in said machine the grind ing means or elements are driven by power at high speed to effect the grinding, they are moved by hand up and down along the knife edge for sharpening the different portions thereof.

One object of this invention is to provide a sharpening mechanism of the type mentioned with practical and desirable means of simple and novel construction for automatically moving the grinding elements or means to and fro along the edge of the knife.

Other objects of the invention are to provide improved means for this purpose applicable particularly to sharpening mechanisms of the general construction disclosed in said application.

Also to provide an improved automatic knife sharpening mechanism for cutting machines which will be quick, efficient and reliable in operation and will preclude uneven or unequal grinding of difierent portions of the knife edge.

Further objects and advantages of the invention will appear from the following specification of the preferred embodiment of the invention,

shown in the accompanying drawings, and the novel features of the invention are set forth in the appended claims.

In said drawings:

Fig. 1 is a front elevation, partly in section, of

scale, on line 33, Fig, 1, but showing the position of. the clutch for downward travel of grinding means.

Fig. 4 is a sectional plan view on line 4-4, Fig. 1.

Fig. 5 is a fragmentary front elevation,,showing the position of the parts during thedownward travel of the grinding means.

Fig. 6 is a similar View showing the parts in position to start the-upward travel of the grinding means.

Fig. '7 is an elevation, partly in section, illustrating thev action of the clutch-actuating spring.

The knife sharpening mechanism, as herein illustrated, is constructed substantially as disclosed in the above-identified application, except as regards the addition thereto or inclusion therein of themeans (hereinafter termed for convenience the traversing'mechanism), which causes the automatic travel of the grinding elements to and fro along the knife edge. The cutting machine and its knife sharpening mechanism, except as hereinafter explained, may be constructed as illustrated in said application, or may be of other known or suitable, construction. As herein disclosed, the machine comprises the usual base It) adapted to rest and be moved about upon the supporting table for the work, an upright standard ll, rising from the base and supporting the stationary'frame l2 of an electric motor whichreciprocates the knife l3 in a guide slot in the front of the standard by means of suitable drive connections, including a crank wheel Mon the front end of the horizontal rotor shaft of the motor. The knife grinding elements or means, as illustrated in the drawings, comprises flexible belts or bands I5 and I6 having abrasive grinding surfaces arranged for grinding contact with opposite sides of the edge portion of the knife, said bands being driven from the knife operating motor, so that the stretches of the bands which contact with the knife travel horizontally past 'the latter, and the bands are mounted on a carriage I! arranged to move up and down lengthwise of the knife so as to enable the sharpening of .the knife edge throughout its full length. I

The drivingmechanism for the grinding means may be briefly described as follows:

20 and 2| represent two vertical shafts arranged in front of therknife at opposite sides of the plane thereof, to rotate and slide axially in suitable bearings. on a cover-piece or housing 22, which is stationarily but removably secured in place at the front of the machine and serves to cover the crank wheel and other parts of the the including threeintermeshing pinions 25, 26 and 1 21, which are held from endwise movement in a chamber 23 in the lower portion of the housing, I

the shafts and 21 being connected to rotate with but slide axially through the pinions 25 and 26, as by keys projecting from the pinions into longitudinal keyways in the shafts. The third pinion 21 may be similarly splined on the lower portion of a third or driving shaft 29 to rotate therewith but permit axial movement of'the shaft through the pinion. This shaft 29 is journalled in suitable bearings in the housing 22, and may be parallel with and at one side. of the two shafts 20 and 2i. At its upper end, the shaft 29' is geared, as. by intermeshing, spiral toothed pinions 3i!- and 3| to a horizontal shaft 32 on i which is fixed awheel 33 arranged to be driven by the crank Wheel I4. The shaft 32 and pinions and BI are suitably mounted in a gear casing 34 arranged above the housing 22 to move vertically toward andfrom the same, as on guide posts, 35. fixed to and rising. from the housing. Gear'casing 34 is pressed downwardly to. releasably hold thewheel 33 in driving engagement withthe crank wheel I4, as by springs 36 surrounding, the posts betweenthe gear casing and nuts or heads at. the upper end of the guide posts. The wheel 33 may bedriven by frictional engagement, with the crank wheel.

Normally, when the sharpening mechanism is notbeing used,'the,grinder carriage IT is held in an inoperativeupper position adjacent the lower end ofthe housing, l2, ashereinafter explained, and, as by upwardpressure against the lower end of the driving'shaft 29, holds the gear. casing 34 up with, the driving wheel 33 out of driving connection with, the crank wheel I4, so that the grinding elements are not driven but remain stationary. When it is desired to sharpen the knife, thegrinder carriage I1 is lowered, as will be explained, causingwheel53 to engage crank wheel l4 anddrive the grinding elements, and the grinder. carriage to be moved downwardly and upwardly along the knife. Reference may be had to the above-identified application for a more detailed description of the construction and op- 1 eration of the sharpening mechanism.

The traversing mechanismor means for moving the grinder carriage up and-down for effecting the sharpening of the knife edge throughout its-length, as herein disclosedJs constructed as follows: a

4!! represents a vertical rack bar or toothed rack which is-fi'xed at its lower end', as by screws 4|, to'the grinder carriage l'l', extends upwardly therefrom, and is adapted toslide. vertically in suitable guideways 42 and-43 on thehousing 22. The rack has teeth which mesh with a toothed pinion 45 secured tofa shaft 46 so that rotation of .the shaft in one direction will move the rack and attached grinder carriage downwardly along the knife edge, while. opposite rotation of the shaft will move the rack and grinder carriage upwardly along the knife edge. Shaft 45 may be arranged'horizontally in front of the rack and suitably journalled on the housing 22. As shown.

the shaft passes through oppositely arranged bevel pinions 41 and 48 which are loose on or adapted to rotate about the shaft and have elongated hubs or sleeves journalled to rotate in bearings 49 on the housing so that the bevel pinions, which may be suitably bushed, constitute bearings for the shaft 46. Meshing with the bevel pinions 41 and 48, is a bevel pinion 50 secured on a shaft 5i, which preferably extends horizontally rearwardly from the shaft 46 and is journalled in a suitable bearing 52 on the housing. Also secured on this shaft 5| is a worm wheel 53 which meshes with and is driven by a worm 54 secured on the vertical shaft 29 which drives the grinding elements.

Suitably splined or mounted on the shaft 46 between the pinions 41 and 48, so as to rotate with the shaft and slide axially thereon, is a clutch sleeve 55. The clutch sleeve has teeth or projections at one end adapted to engage with cooperating teeth 56 on the pinion 41 for rotating said pinion, and at its opposite end has teeth or projections adapted to engage teeth 51 on the other pinion 48 for rotating the latter. By shiftthe clutch sleeve toward the bevel pinion 41, this pinion is coupled to and adapted to rotate the shaft 45 in one direction, while by shifting the clutch sleeve toward the other bevel pinion 48, the latter is coupled to and adapted to rotate the shaft 46 in the opposite direction, to thus produce upward or downward travel of the rack and grinder carriage, depending upon whether the clutch sleeve is shifted to one or the other of its pinion-driving positions.

The clutch is shifted for thus effecting up or down travel of the grinder carriage, preferably by an operating lever 65, which is suitably fulcrumed between its ends, and has an arm 6| pivoted to a yoke 62 which straddles the clutch sleeve in a circumferential groove therein. Preferably, the lever is fulcrumed on a pivot 63 fixed on housing 22 within a cover 64 which may be a part of or formed by a separate cover-piece secured to the housing 22 and covers the rackactuating gearing. The other arm of the lever projects out through a suitable opening in one side of the cover and may be provided with a finger-piece 65 at its outer end for actuating the lever to shift the clutch.

Normally, when the knife sharpening means are. out of action or stationary, the clutch-operating lever 65 is releasably held by a suitable spring 66 in the position shown in Fig. l, in which. the clutch couples the bevel pinion 41 to the shaft 46. The clutch-holdingspring 66, as shown, is a compression coil spring surrounding a rod 61 and hearing at its ends against a shoulder on the rod and against a stud 68 on the housing 22. Rod 6'! is pivoted at one end on a stud 69 on the lever 50 and at its other end is adapted to slide endwise in a hole in the stud 68, with the rod either adapted to rock in said hole, or said stud adapted to pivot to permit rod 61 to swing with the lever when the latter is actuated. When the clutch lever is moved to shift the clutch 55, the stud 69 thereon will pass from a position at one side of a dead center line extending through the centers of the lever fulcrum 63 and the fixed stud 58 to a position at the 0pposite side of said dead center line. Thus, the spring will act to quickly shift or snap the clutch and releasably hold it either in the position shown in Fig. l, in which the bevel gear 41 is coupled to the shaft 45, or in the position shown in Fig. 5, in which the other bevel gear 48 is coupled to the shaft 46.

Assuming the parts to be in the inactive position shown in Fig. 1, with the grinder carriage in its uppermost position and holding the drive wheel 33 up out of engagement with the motor crank wheel l4, and bevel pinion 4'! coupled by clutch 55 to the rack-actuating shaft 46, then if clutch lever 50 is raised, the clutch will free the bevel pinion 41, thus permitting rack 40 to lower and wheel 33 to engage the motor-driven crank wheel I4, and the clutch will couple the other bevel pinion 48 to the rack-actuating shaft 46. The grinding means or elements will be thus set in motion for sharpening the knife, provided the motor has been switched on, or is running. Also, drive shaft 29 for the grinding means will, through the described worm and bevel gearing, rotate the shaft 46 in a direction to move rack 40 and the grinder carriage downwardly. As the carriage approaches the intended limit of its downward movement, a trip projection or stud on the rack 40 will strike and depress the long arm of clutch lever 60, whereupon the clutch-actuating spring 66 will act to quickly snap or throw the clutch 55 over to couple the first bevel pinion 41 to the shaft 46, and thus cause the return or upward movement of the rack and grinder carriage. As the grinder carriage approaches the intended upward limit of its movement, it engages the lower end of the driving shaft 29 and lifts the latter and the gear casing 34 to disengage the wheel 33 from the motor-driven crank wheel I4, thereby stopping the rotation of shaft 29 and thus arresting the motion of the grinding means and also of the traverse mechanism which causes the travel of the grinding means lengthwise of the knife edge, and leaving the parts arrested or inactive in the position shown in Fig. 1, ready to be again actuated for starting the sharpening mechanism when it is again necessary to sharpen the knife.

It will be noted that in the operation of the sharpening mechanism as disclosedherein, the grinding means or elements travel first downwardly along the knife edge and then upwardly, and the motion of the driving and traversing mechanism for the grinding means is arrested when the grinder carriage is returned to its upper position, shown in Fig. 1, after one downward movement, so that the grinding means are thrown out of action after moving only once downwardly and upwardly along the knife. The grinding elements grind very rapidly and one down and up movement thereof along the knife is ordinarily sufilcient to put the required edge on the knife, and the grinding means are thrown out of action after this single up and down movement to' prevent undue grinding of the knife. Furthermore, the described snap action reversing means operates to effect the reversal of travel of the grinder carriage very quickly when it has reached the limit of its downward travel. This prevents a dwell or arrested motion of the grinder carriage between its downward and upward movements which, if permitted to occur, would result in grinding the lower end of the knife edge to a greater extent than other portions thereof, with the result that a concaved edge would be ground in the lower end portion of the knife. Should the knife be so (11:11 that it is necessary to cause the grinding means to travel downwardly and upwardly more than once, to produce the required keen edge on the knife, the downward and upward motions of the grinding means can be repeated by successive operations of the clutch operating lever 60, but in the ordinary use of the machine, the sharpening mechanism is thrown out of action after the grinder carriage has travelled once downwardly and upwardly along the knife edge. The described automatic traversing mechanism is exceedingly simple and adds but a few parts to a sharpening mechanism such as shown in said pending application, in which the grinding means are moved by hand lengthwise along the knife edge; and by the use of the rack secured to the grinder carriage and sliding in guides on the stationary machine frame, on which the rack-operating gearing is mounted, a very sturdy, reliable and durable automatic sharpener is provided.

In the sharpening mechanism as herein disclosed, the knife is sharpened by flexible grinding belts and the front supporting and driving pulleys 23 and 24, for these belts are fixed directly to the lower ends of the shafts 20 and 2|, both of which slide with the grind-er carriage in the up and down travel thereof, lengthwise of the knife edge. This construction makes an eflicient and desirable sharpening mechanism in which the two shafts cooperate in guiding the carriage up and down and preventing twisting or lateral motion of the same. It will be understood, however, that this invention is not restricted to sharpening mechanisms employing flexible band grinding means, but that grinding means or elements of other kinds could be em ployed and operated by the driving mechanism disclosed, and also that the improvements are not confined in application to a construction in which the grinding elements are directly connected to or supported by two sliding shafts, such as 20 and 2|, since band grinding means, such as shown, or other grinding elements, could be operated, for example, by a single, vertically movable shaft geared to the grinding elements,

as disclosed in U, S. Patent No. 2,183,787, issued,

December 19, 1939, to Frederick J. Clark, assignor to Eastman Machine Company.

We claim:

1. In a knife sharpening mechanism for cutting machines, comprising knife grinding means, a carriage for said means movable lengthwise of the knife edge for presenting the grinding means to different portions of the edge, and drive mechanism for the grinding means, traversing mechanism for causing the carriage to travel to and fro lengthwise of the knife edge comprising a rack and pinion, said rack being movable with said carriage, oppositely driven gears for rotating said pinion in opposite directions, a clutch operable for couplingone or the other of said gears to said pinion, an operating device for shifting said clutch to couple one of said gears to said pinion and move the rack in one direction, and a trip operated by the rack and arranged to actuate said operating device and shift the clutch for coupling said other gear to said pinionfor reversing the direction of movement of the rack.

2. In a knife sharpening mechanism for cutting machines, comprising knife grinding means, a carriage for said means movable lengthwise of the knife edge for presenting the grinding means to different portions of the edge, and drive mechanism for the grinding means, traversing mechanism for causingthe carriage to travel to and fro lengthwise of the knife edge comprising a toothed rack movable with said carriage, a driven.

shaft, a pinion connected with said shaft and meshing with said rack, oppositely driven gears rotatable relatively to said shaft, a clutch for coupling one or the other of said gears to said shaft for turning the shaft in opposite directions, a device operable for actuating said clutch to couple one of said gears to the shaft for causing travel of said rack in one direction, and a trip which is operated by said rack and actuates said operating device and clutch to couple said other gear to said shaft and reverse the direction of movement of the rack.

3. In a knife sharpening mechanism for cutting machines, comprising knife grinding means, a carriage for said means movable lengthwise of the knife edge for presenting the grinding means to different portions of the edge, and drive mechanism for the grinding means, traversing mechanism for causing the carriage to travel to and fro lengthwise of the knife edge comprising a rack and pinion, said rack being secured to and movable with said carriage, a shaft connected with said pinion, oppositely arranged bevel gears rotatable on said shaft, a clutch rotatable with but shiftable on said shaft to couple one or the other of said bevel gears to the shaft, and a clutch operating device operable for actuating the clutch to couple one bevel gear to said shaft for causing travel of said rack in one direction, and a trip connected to said rack and arranged to engage said operating device and shift the clutch for coupling said other bevel gear to said shaft for reversing the direction of travel of said rack.

4. In a knife sharpening mechanism for cutting machines, comprising knife grinding means, a carriage for said means movable lengthwise of the knife edge for presenting the grinding means to different portions of the edge, and drive mechanism for the grinding means, traversing mechanism driven by said drive mechanism for causing the carriage to travel to and fro lengthwise of the knife edge comprising a rack and pinion, said rack being movable with the carriage, oppositely driven gears for rotating said pinion and moving said rack in opposite directions, a clutch for coupling one or the other of said gears to said pinion, an operating device operable for actuating said clutch to couple one of said gears to said pinion for moving said rack in one direction, and a trip operated by said rack and arranged to actuate said operating device and shift said clutch to couple said other gear with said pinion for reversing the direction of travel of the rack.

5. In a knife sharpening mechanism for cutting machines, comprising knife grinding means,

a carriage for said means movable lengthwise of the knife edge for presenting the grinding means to different portions of the edge, and drive mechanism for the grinding means, traversing mechanism for causing the carriage to travel to and fro lengthwise of the knife edge comprising a rack and pinion, said rack being movable with said carriage, oppositely driven gears for oppositely rotating said pinion to move said rack in opposite directions, a clutch operable for coupling one or the other of said gears to said pinion, a device operable for actuating said clutch to couple one of said gears to said pinion for causing said rack to travel in one direction, a trip arranged to actuate said operating device when said rack nears the end of its travel in said direction and actuate said clutch to couple said other gear with said pinion for reversing the direction of travel of the rack, and means actuated by the movement of the carriage for arresting said traversing mechanism at the end of its travel in said last mentioned direction.

6. In a knife sharpening mechanism for cutting machines, comprising knife grinding means, a carriage for said means movable lengthwise of the knife edge for presenting the grinding means to different portions of the edge, and drive mechanism for the grinding means, traversing mechanism for causing the carriage to travel to and fro lengthwise of the knife edge comprising a rack and pinion, said rack being movable with said carriage, a clutch and gearing operating by different actions of said clutch to drive said pinion in opposite directions, a clutch operating device operable for actuating said clutch to cause said rack to travel in one direction, and a trip device attached to and movable with said rack and arranged to engage and move said operating device to actuate said clutch for reversing the direction of travel of said rack.

7. In a knife sharpening mechanism for cutting machines, comprising knife grinding means, a carriage for said means movable lengthwise of the knife edge for presenting the grinding means to different portions of the edge, and drive mechanism for the grinding means, traversing mechanism for causing the carriage to travel to and fro lengthwise of the knife edge comprising a rack and pinion, said rack being movable with said carriage, a clutch and gearing operating by different actions of said clutch to driv said pinion in opposite directions, a clutch operating device operable for actuating said clutch to cause said rack to travel in one direction, a trip device constructed and arranged to move said operating device to actuate said clutch for reversing the direction of travel of said rack, and means constructed and arranged to arrest said sharpening mechanism at the end of the first revers travel of said rack arm carriage.

8. In a knife sharpening mechanism for cutting machines, comprising knife grinding means, a carriage for said means movable lengthwise of the knife edge for presenting the grinding means to different portions of the edge, and drive mechanism for the grinding means, traversing mechanism for causing the carriage to travel to and fro lengthwise of the knife edge comprising a rack and pinion, said rack being movable with said carriage, a clutch and gearing operating by different actions of said clutch to drive said pinion in opposite directions, a clutch operating device operable for actuating said clutch to cause said rack to travel in one direction, a trip device connected to and movable with said rack and arranged to move said operating device to actuate said clutch for reversing the direction of travel of said rack, and a snap action spring device operatively connected with said clutch operating device and having its spring arranged to be strained by an initial movement of the operating device and to act after said initial movement to quickly throw the clutch to one or another operative position depending upon the direction of movement of the operating device,

9. In a knife sharpening mechanism for cutting machines, comprising knife grinding means, a carriage for said means movable lengthwise of the knife edge for presenting the grinding means to different portions of the edge, and drive mechanism for the grinding means, traversing mechanism for causing the carriage to trave1 to and fro lengthwise of the knife edge comprising a rack and pinion, said rack being movable with said carriage, a clutch and gearing operating by different actions of said clutch to drive said pinion in opposite directions, a pivoted clutch operating device operable for actuating said clutch to cause said rack to travel in one direction, a trip device constructed and arranged to move said operating device to actuate said clutch for reversing the direction of travel of said rack, and a snap action spring device comprising a rod pivotally connected to said operating device and to a stationarily positioned stud, and a spring surrounding said rod between a shoulder thereon and said stud, the pivotal connection of said rod with said operating device being arranged to cross a dead center line extending through the centers of the pivot for said operating device and said stud for releasably holding said operating device in either of two difierent positions, and quickly throwing the same to either position after an initial movement of said device partway toward said position. i

10. In a knife sharpening mechanism for cutting machines, comprising knife grinding means, a carriage for said means movable lengthwise of the knife edge for presenting the grinding means to difierent portions of the edge, and drive mechanism for the grinding means, traversing mechanism for causing the carriage to travel to and fro lengthwise of the knife edge comprising a rack and pinion, said rack being connected to said carriage to move therewith, oppositely driven gears for oppositely rotating said pinion to move said rack and carriage in opposite directions, a clutch operable for coupling one of said gears to said pinion for causing said rack to travel in ene direction, a trip connected to and movable with said rack, and means operated by said trip and arranged to actuate said clutch when said carriage nears the end of its travel in said direction to uncouple said one gear from and couple said other gear with said pinion for reversing the direction of travel of the rack.

11. In a knife sharpening mechanism for cutting machines, comprising knife grinding means, a carriage for said means movable lengthwise of the knife edge for presenting the grinding means to different portions of the edge, and drive mechanism for the grinding means, traversing mechanism for causing the carriage to travel to and fro lengthwise of the knife edge comprising a bar connected to and movable with said carriag and a wheel in propelling engagement with said bar, oppositely driven gears for oppositely rotating said wheel to move said bar and carriage in opposite directions, a clutch operable for coupling one of said gears to said wheel for causing said bar and carriage to travel in one direction, a trip device connected to and movable with said bar,

means operated by said trip device and arranged to actuate said clutch when said carriage nears the end of its travel in said one direction to uncouple said one gear from and coupl said other gear with said wheel for reversing the direction of travel of the bar, and means controlled by the movement of the carriage for arresting said traversing mechanism at the end of its travel in said last mentioned direction.

FREDERICK J. CLARK.

CARL F. HILGEMAN. 

